JPWO2010073373A1 - Power steering device - Google Patents

Abstract

The power steering device is preferably used for setting an additional friction torque to be applied to the steering based on an actual steering angle, a target steering angle, and the like and performing control for applying the additional friction torque. Specifically, the additional friction torque changing means changes the additional friction torque according to the behavior control of the vehicle when the behavior control of the vehicle works. Thereby, it becomes possible to suppress interference between the behavior control of the vehicle and the control for applying the additional friction torque (friction applying control).

Description

  The present invention relates to a power steering apparatus that controls an additional friction torque applied to a steering.

  This type of technique is proposed in Patent Document 1, for example. Patent Document 1 proposes a technique for applying a friction torque according to the steering angle and the vehicle speed to the steering in order to improve the return characteristic of the steering at a low speed and to improve the convergence of the steering at a high speed. Yes.

JP 2002-104210 A

  By the way, conventionally, as vehicle behavior control, control such as traction control, anti-lock brake, and traction control has been performed. Such vehicle behavior control and control for applying the additional friction torque as described above. May interfere with each other. For example, it is conceivable that smooth control cannot be performed or the effect of vehicle behavior control is reduced. Note that the above-mentioned Patent Document 1 does not describe such problems and solutions.

  The present invention has been made to solve the above-described problems, and is a power steering device capable of appropriately suppressing interference between control of additional friction torque applied to a steering and behavior control of a vehicle. The purpose is to provide.

  In one aspect of the present invention, a power steering device that sets an additional friction torque to be applied to a steering based on an actual steering angle and a target steering angle and performs control for applying the additional friction torque is provided for vehicle behavior control. An additional friction torque changing means for changing the additional friction torque in accordance with the behavior control of the vehicle is provided.

  The power steering device is preferably used for setting an additional friction torque to be applied to the steering based on an actual steering angle, a target steering angle, and the like, and performing control for applying the additional friction torque. Specifically, the additional friction torque changing means changes the additional friction torque according to the behavior control of the vehicle when the behavior control of the vehicle works. Thereby, it becomes possible to suppress the interference between the behavior control of the vehicle and the control for applying the additional friction torque (friction applying control).

  In one aspect of the power steering apparatus described above, the behavior control of the vehicle corresponds to traction control, and the additional friction torque changing means is more effective when the traction control is activated than when the traction control is not activated. Thus, the additional friction torque is increased. Thereby, interference with traction control and friction provision control can be suppressed appropriately.

  In another aspect of the power steering apparatus described above, the behavior control of the vehicle corresponds to control of an anti-lock brake, and the additional friction torque changing unit is configured to control the anti-lock when the control of the anti-lock brake works. The additional friction torque is increased as compared with the case where the brake control does not work. Thereby, interference with the control of an anti-lock brake and friction provision control can be suppressed appropriately.

  In another aspect of the power steering device described above, the behavior control of the vehicle corresponds to vehicle stability control, and the additional friction torque changing means is configured to control the vehicle stability control when the vehicle stability control is activated. The additional friction torque is increased as compared with the case where the motor does not work. Thereby, interference with vehicle stability control and friction provision control can be suppressed appropriately.

  In another aspect of the power steering device described above, the behavior control of the vehicle corresponds to vehicle integrated control, and the vehicle integrated control does not work when the vehicle integrated control works. The additional friction torque is reduced as compared with the case. Thereby, interference with vehicle integrated control and friction provision control can be suppressed appropriately.

  In another aspect of the power steering apparatus described above, the behavior control of the vehicle corresponds to lane keep assist control, and the additional friction torque changing means is configured to perform the lane keep assist when the lane keep assist control is activated. The additional friction torque is reduced as compared with the case where the assist control does not work. Thereby, interference with control of lane keep assist and friction provision control can be suppressed appropriately.

  In another aspect of the above-described power steering apparatus, the behavior control of the vehicle corresponds to adaptive cruise control, and the additional friction torque changing means does not operate the adaptive cruise control when the adaptive cruise control operates. The additional friction torque is reduced as compared with the case. Thereby, interference with adaptive cruise control and friction provision control can be suppressed appropriately.

1 is a schematic configuration diagram of a steering control system to which a power steering apparatus according to an embodiment is applied. An example of a method for obtaining the friction torque will be described. An example of the characteristic of additional friction torque is shown. It is an image figure showing the characteristic of additional friction torque with a visible model. It is a flowchart which shows the control processing in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Steering angle sensor 4 Steering torque sensor 5 Pinion 6 Steering rack 7 Motor 8 Motor rotation angle sensor 12 Wheel 15 Vehicle speed sensor 30 Controller 50 Steering control system

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Device configuration]
First, the overall configuration of a system 50 (hereinafter referred to as a “steering control system”) to which the power steering apparatus according to the present embodiment is applied will be described. FIG. 1 is a schematic diagram showing the configuration of the steering control system 50.

  The steering control system 50 mainly includes a steering wheel 1, a steering shaft 2, a steering angle sensor 3, a steering torque sensor 4, a pinion 5, a steering rack 6, a motor 7, and a motor rotation angle sensor 8. Tie rods 10R and 10L, knuckle arms 11R and 11L, wheels (front wheels) 12FR and 12FL, a vehicle speed sensor 15, and a controller 30. In the following, “R” and “L” added to the end of the reference numerals of the tie rods 10R and 10L, the knuckle arms 11R and 11L, and the wheels 12FR and 12FL will be omitted if they are used without distinction. And

  The steering control system 50 is configured by an electric power steering (EPS) system. Specifically, the steering control system 50 is a system that is mounted on a vehicle and performs control for turning the wheels 12F (steered wheels) in accordance with the operation of the steering wheel 1 or the like.

  The steering wheel 1 is operated by the driver to turn the vehicle. The steering wheel 1 is connected to a pinion 5 via a steering shaft 2. The steering shaft 2 is mainly provided with a steering angle sensor 3 and a steering torque sensor 4. Hereinafter, the steering wheel 1 is also simply referred to as “steering”.

  The pinion 5 is configured to be rotatable according to the rotation of the steering shaft 2, and the steering rack 6 is configured to be movable according to the rotation of the pinion 5. A knuckle arm 11 is connected to the steering rack 6 via a tie rod 10, and wheels 12 </ b> F are connected to the knuckle arm 11. In this case, when the tie rod 10 and the knuckle arm 11 are operated by the steering rack 6, the wheels 12F connected to the knuckle arm 11 are steered.

  The motor 7 is composed of a three-phase AC motor, for example, and is provided coaxially with the steering rack 6 in a steering gear box (not shown). The motor 7 is configured to be able to apply a force that assists the movement of the steering rack 6 or a force that inhibits the movement of the steering rack 6. Specifically, the motor 7 applies assist torque in the steering direction by the driver in order to improve the steering feeling, the steering stability, and the like. On the other hand, the motor 7 applies an additional friction torque in a direction opposite to the steering direction by the driver (that is, applies a steering reaction force) in order to improve the steering performance. The motor 7 is controlled by a control signal S7 supplied from the controller 30.

  Various sensors provided in the steering control system 50 function as follows. The steering angle sensor 3 detects a steering angle (corresponding to an actual steering angle) corresponding to the operation of the steering wheel 1 by the driver, and supplies a detection signal S3 corresponding to the detected steering angle to the controller 30. The steering torque sensor 4 detects the steering torque input by the driver, and supplies a detection signal S4 corresponding to the detected steering torque to the controller 30. The motor rotation angle sensor 8 detects the rotation angle of the motor 7 and supplies a detection signal S8 corresponding to the detected rotation angle to the controller 30. The vehicle speed sensor 15 detects the vehicle speed (for example, detects the wheel speed), and supplies a detection signal S15 corresponding to the detected vehicle speed to the controller 30.

  The controller 30 includes a CPU, a ROM, a RAM, an A / D converter, and the like (not shown). The controller 30 controls the motor 7 by supplying a control signal S7 to the motor 7 based on the detection signals S3, S4, S8, S15 and the like supplied from the various sensors described above. In the present embodiment, the controller 30 performs control for applying an additional friction torque to the steering from the motor 7 (hereinafter referred to as “friction application control”). Thus, the controller 30 functions as a power steering device in the present invention. Specifically, the controller 30 operates as an additional friction torque changing unit. The controller 30 may be realized by an ECU (Electronic Control Unit) that performs control in the vehicle.

[Example of friction application control]
Next, an example of friction application control performed by the controller 30 will be described. First, the controller 30 determines the friction torque (hereinafter referred to as “Tt”) to be applied to the steering based on the steering angle (hereinafter referred to as “θ”) and the vehicle speed (hereinafter referred to as “V”). ). Next, the controller 30 obtains a target steering angle (hereinafter referred to as “θt”) based on the steering angle θ and the friction torque Tt. Next, the controller 30 obtains an additional friction torque (hereinafter referred to as “Tc”) based on a deviation (hereinafter referred to as “Δθ”) between the target steering angle θt and the steering angle θ. That is, the controller 30 corrects the friction torque Tt based on the target steering angle θt and the like, and sets the corrected friction torque as the additional friction torque Tc. Then, the controller 30 controls the motor 7 so that the additional friction torque Tc thus obtained is applied to the steering.

  Here, with reference to FIG. 2 thru | or FIG. 4, friction provision control is demonstrated concretely.

  FIG. 2 is a diagram showing an example of a method for obtaining the friction torque Tt. FIG. 2 shows the steering angle θ on the horizontal axis and the friction torque Tt on the vertical axis. More specifically, FIG. 2 corresponds to a map in which the friction torque Tt to be set with respect to the steering angle θ according to the vehicle speed V is defined. Here, as an example, maps corresponding to the high speed region V2, the medium speed region V1, and the low speed region V0 are shown. The controller 30 obtains the friction torque Tt corresponding to the current steering angle θ and the vehicle speed V by referring to such a map.

  According to the map shown in FIG. 2, the friction torque Tt having a larger value is set as the vehicle speed increases for the same steering angle θ. This is because, in the high speed region V2 and the medium speed region V1, it is preferable to generate a certain amount of friction torque from the viewpoint of improving the straight running stability and reducing the steering holding force and improving the stability at the time of steering. This is because at V0, if the friction torque is large, the driver may feel uncomfortable and the steering feeling may deteriorate. Further, according to the map shown in FIG. 2, when the vehicle speed is the same or in the same vehicle speed range, the larger the steering angle θ, the larger the friction torque Tt that is set. This is because when the steering angle θ is large, the turning angle of the wheel becomes large, so that a large lateral force is likely to be generated, and from the viewpoint of reducing the holding force and improving the stability during steering holding, a larger friction torque This is because it is necessary.

  Next, a method for obtaining the target steering angle θt from the friction torque Tt obtained as described above will be described. Based on the deviation Δθ (= θt−θ) between the target steering angle θt and the steering angle θ, and the deviation upper limit value Δ (= Tt / K) defined by the friction torque Tt and the gain K, the controller 30 A steering angle θt is obtained. Specifically, the controller 30 first initializes the target steering angle θt to θ (if the initialization has been completed, the initialization is not performed), and then obtains the deviation Δθ (= θt−θ), and “Δθ> Δ”. The target steering angle θt is changed to “θt = θ + Δ”, and when “Δθ <−Δ”, the target steering angle θt is changed to “θt = θ−Δ” and “−Δ ≦ Δθ ≦ Δ ”, The target steering angle θt is not changed. The gain K is a value determined in consideration of the rigidity of the steering system, for example.

  Next, a method for obtaining the additional friction torque Tc from the target steering angle θt obtained as described above will be described. The controller 30 obtains the additional friction torque Tc from the deviation Δθ (= θt−θ) obtained from the target steering angle θt and the gain K (= Tt / Δ). Specifically, the controller 30 obtains the additional friction torque Tc from “Tc = K · Δθ”, that is, “Tc = K (θt−θ)”.

FIG. 3 is a diagram illustrating an example of the characteristic of the additional friction torque Tc. FIG. 3 shows the steering angle θ on the horizontal axis and the additional friction torque Tc on the vertical axis (the counterclockwise torque direction is positive and the clockwise torque direction is negative). Here, a case where the friction torque Tt is “Tt ₁ ” and a case where the friction torque Tt is “Tt ₂ ” (Tt ₂ <Tt ₁ ) is shown as an example. For example, the friction torque Tt ₁ when the vehicle speed is high speed range V2 or middle speed range V1, the vehicle speed indicates the friction torque Tt ₂ in case of the low speed range V0 (see FIG. 2). In FIG. 3, in both cases of “Tt ₁ ” and “Tt ₂ ”, for the sake of easy understanding, for the sake of convenience, the target steering angle θt is the same and does not change according to the change of the steering angle θ. To do. When the target steering angle θt changes, the graph simply translates in the horizontal axis direction around the new target steering angle θt accordingly.

As shown in FIG. 3, since the deviation upper limit value Δ is “Δ = Tt / K”, the deviation upper limit value Δ _{1 in} the case of “Tt ₁ ” increases as the friction torque Tt increases. It is larger than the deviation upper limit Δ _{2 in} the case of “Tt ₂ ”). Further, in the range of “−Δ ≦ Δθ ≦ Δ”, the target steering angle θt is maintained without being changed, and an additional friction torque is obtained from “Tc = K · Δθ”, that is, “Tc = K (θt−θ)”. The magnitude of Tc increases in proportion to Δθ. In the range of “Δθ> Δ” and “Δθ <−Δ”, the target steering angle θt is changed as described above, and the magnitude of Δθ becomes constant. Therefore, “Tc = K · Δθ”, that is, “ From “Tc = K (θt−θ)”, the magnitude of the additional friction torque Tc becomes a constant value corresponding to the friction torque Tt. In this case, in the range of “−Δ ≦ Δθ ≦ Δ”, the friction torque Tt to be applied to the steering wheel 1 is not actually applied to the steering wheel 1, and the absolute value of Δθ is greater than or equal to the deviation upper limit value Δ. For the first time, the magnitude of the additional friction torque Tc is set to the magnitude of the friction torque Tt to be applied to the steering wheel 1. The reason why the friction torque Tt is not applied in the range of “−Δ ≦ Δθ ≦ Δ” is to prevent the friction torque from being easily vibrated and deteriorating the steering feeling.

  FIG. 4 is an image diagram showing the characteristic of the additional friction torque Tc with a visible model. FIG. 4A is an image diagram corresponding to a range of “−Δ ≦ Δθ ≦ Δ”. In this case, the target steering angle θt does not change, and a force that balances against the force T (for example, an external force generated due to an input to the wheel), that is, a spring with a spring constant K (= gain K). An elastic force (= K · Δθ) is generated when displaced by a displacement amount (θt−θ). FIG. 4B is an image diagram corresponding to ranges of “Δθ> Δ” and “Δθ <−Δ”. In this case, the target steering angle θt changes in a direction to receive the force T, and a constant frictional force Tt ′ (<force T) is generated in a direction opposite to the force T. The frictional force Tt ′ corresponds to a value obtained by converting the frictional force Tt into a force.

[Control method in this embodiment]
Next, a control method performed by the controller 30 in the present embodiment will be described. In this embodiment, when the behavior control of the vehicle works, the controller 30 changes the additional friction torque determined by the method described above according to the behavior control of the vehicle. Specifically, the controller 30 performs vehicle behavior control such as traction control, anti-lock brake control, vehicle stability control, vehicle integration control, lane keep assist control, and adaptive cruise control. Further, the friction applying control is executed by changing the additional friction torque according to the behavior control of the vehicle.

  This is because it is possible that the behavior control of the vehicle interferes with the friction application control if the friction application control using the additional friction torque is performed as it is while the behavior control of the vehicle is being performed. For example, it is conceivable that smooth vehicle behavior control cannot be performed or the effect of vehicle behavior control is reduced. Therefore, in the present embodiment, when the vehicle behavior control is performed to suppress the interference between the vehicle behavior control and the friction application control, the additional friction torque determined by the above-described method is changed. Friction application control is executed.

  Below, traction control (TRC), anti-lock brake (ABS) control, vehicle stability control (VSC), vehicle integrated control (VDIM), lane keep assist (LKA) control, adaptive cruise control (ACC), respectively The control method performed when is working will be specifically described.

(When TRC is working)
First, a method of changing the additional friction torque performed when the traction control is working will be described. The traction control corresponds to the traction control performed on the road surface where the wheels are likely to idle.

  In the present embodiment, the controller 30 increases the additional friction torque when the traction control is working compared to when the traction control is not working. That is, the hysteresis width is increased. Specifically, the controller 30 acquires a control flag for traction control (hereinafter referred to as “TRC control flag”) from an ECU or the like in the vehicle, and when the TRC control flag is on, the additional friction is obtained. Control to increase torque. This is to reduce the reaction force transmitted from the wheel 12 or the like to the steering wheel 1 when the traction control is working, and to suppress the uncomfortable feeling at the time of steering due to the reaction force torque.

  More specifically, the controller 30 performs control to gradually increase the additional friction torque when the TRC control flag is turned on. The reason for this is to prevent the steering torque from feeling uncomfortable. Specifically, the controller 30 quickly increases the additional friction torque when the steering angle is near the neutral position, and gradually increases the additional friction torque when the steering angle is relatively large. In addition, when the TRC control flag is turned from on to off, the controller 30 performs control to gradually reduce the additional friction torque. This is for suppressing the occurrence of discomfort at the time of return.

  FIG. 5 is a flowchart illustrating an example of the control process in the present embodiment. This processing controls the additional friction torque according to the operating state of the traction control. Specifically, when the TRC control flag is on, the control mode is set to gradually increase the additional friction torque (hereinafter referred to as “friction application mode”), and is added when the TRC control flag is off. The control mode (hereinafter referred to as “friction application stop mode”) for gradually reducing the friction torque is set. This process is repeatedly executed by the controller 30 after the engine is started.

  First, in step S101, the controller 30 acquires the current TRC control flag. The TRC control flag indicates whether the traction control is on or off. Then, the process proceeds to step S102. In step S102, the controller 30 determines whether or not the TRC control flag acquired in step S101 is on.

  If the TRC control flag is on (step S102; Yes), the process proceeds to step S103. In this case, the controller 30 sets the friction applying mode in which the additional friction torque is gradually increased (step S103). Then, the process proceeds to step S105. On the other hand, when the TRC control flag is off (step S102; No), the process proceeds to step S104. In this case, the controller 30 sets the friction application stop mode in which the additional friction torque is gradually reduced (step S104). Then, the process proceeds to step S105.

  In step S105, the controller 30 stores the current TRC control flag and sets the TRC control flag as a previous stage flag. Then, the process proceeds to step S106. In step S106, the controller 30 determines whether or not the engine is on. If the engine is on (step S106; Yes), the process proceeds to step S107. If the engine is off (step S106; No), the process ends.

  In step S107, the controller 30 acquires the current TRC control flag. Then, the process proceeds to step S108. In step S108, the controller 30 determines whether or not the current TRC control flag acquired in step S107 is different from the previous TRC control flag. If the flags are different (step S108; Yes), the process proceeds to step S110. On the other hand, when the flags are the same (step S108; No), the process proceeds to step S109. In this case, the controller 30 maintains the current friction application control (step S109). Specifically, when the friction application mode is set, the additional friction torque is gradually increased, and when the friction application stop mode is set, the additional friction torque is gradually decreased. Do. And a process returns to step S105 and performs the process mentioned above again.

  In step S110, the controller 30 determines whether or not the TRC control flag acquired in step S107 is on. If the TRC control flag is on (step S110; Yes), the process proceeds to step S111. In this case, the controller 30 sets the friction applying mode in which the additional friction torque is gradually increased (step S111). Then, the process returns to step S105. On the other hand, when the TRC control flag is off (step S110; No), the process proceeds to step S112. In this case, the controller 30 sets the friction application stop mode in which the additional friction torque is gradually reduced (step S112). Then, the process returns to step S105.

  According to the process demonstrated above, interference with traction control and friction provision control can be suppressed appropriately. Specifically, when the traction control is activated, the reaction force transmitted from the wheel 12 to the steering wheel 1 can be reduced, and the uncomfortable feeling during steering due to the reaction force torque can be suppressed.

(When ABS is working)
Next, a method for changing the additional friction torque performed when the anti-lock brake control is working will be described. The anti-lock brake control corresponds to control for preventing the wheels 12 from being locked during braking.

  In the present embodiment, the controller 30 increases the additional friction torque when the antilock brake control is working, compared to when the antilock brake control is not working. That is, the hysteresis width is increased. Specifically, the controller 30 acquires a control flag (hereinafter referred to as “ABS control flag”) for controlling the antilock brake from an ECU in the vehicle, and when the ABS control flag is on, Control to increase the additional friction torque. This is to reduce the reaction force transmitted from the wheel 12 or the like to the steering wheel 1 when the anti-lock brake control is working, and to suppress the uncomfortable feeling during the steering due to the reaction force torque. .

  More specifically, the controller 30 performs control to gradually increase the additional friction torque when the ABS control flag is turned on. The reason for this is to prevent the steering torque from feeling uncomfortable. Specifically, the controller 30 quickly increases the additional friction torque when the steering angle is near the neutral position, and gradually increases the additional friction torque when the steering angle is relatively large. In addition, when the ABS control flag is turned off from on, the controller 30 performs control to gradually reduce the additional friction torque. This is for suppressing the occurrence of discomfort at the time of return.

  By controlling the additional friction torque when the antilock brake control is operating as described above, it is possible to appropriately suppress the interference between the antilock brake control and the friction applying control.

(When VSC is working)
Next, a method for changing the additional friction torque performed when vehicle stability control is working will be described. Vehicle stability control corresponds to control for preventing vehicle spin by suppressing the vehicle body slip angle.

  In the present embodiment, the controller 30 increases the additional friction torque when the vehicle stability control is working, compared to when the vehicle stability control is not working. That is, the hysteresis width is increased. Specifically, the controller 30 obtains a vehicle stability control control flag (hereinafter referred to as “VSC control flag”) from an ECU or the like in the vehicle, and when the VSC control flag is on, Control to increase the additional friction torque. This is to reduce the reaction force transmitted from the wheel 12 or the like to the steering wheel 1 when the vehicle stability control is working, thereby suppressing the uncomfortable feeling during the steering due to the reaction force torque.

  More specifically, the controller 30 performs control to gradually increase the additional friction torque when the VSC control flag is turned on. The reason for this is to prevent the steering torque from feeling uncomfortable. Specifically, the controller 30 quickly increases the additional friction torque when the steering angle is near the neutral position, and gradually increases the additional friction torque when the steering angle is relatively large. In addition, when the VSC control flag is turned from on to off, the controller 30 performs control to gradually reduce the additional friction torque. This is for suppressing the occurrence of discomfort at the time of return.

  In this way, when the vehicle stability control is working, the interference between the vehicle stability control and the friction applying control can be appropriately suppressed by controlling the additional friction torque.

(When VDIM is working)
Next, a method for changing the additional friction torque performed when the vehicle integrated control is working will be described. The vehicle integrated control corresponds to control performed to improve the stability and motion performance of the vehicle by comprehensively controlling brakes and traction.

  In the present embodiment, the controller 30 reduces the additional friction torque when the vehicle integrated control is working compared to when the vehicle integrated control is not working. That is, the hysteresis control level is lowered. Specifically, the controller 30 acquires a control flag (hereinafter referred to as “VDIM control flag”) for vehicle integrated control from an ECU or the like in the vehicle, and is added when the VDIM control flag is on. Control to reduce the friction torque. This is to suppress the influence of the steering system when the vehicle integrated control is working.

  In this way, when the vehicle integrated control is working, the interference between the vehicle integrated control and the friction applying control can be appropriately suppressed by controlling the additional friction torque.

  Note that, when the vehicle integrated control is working, the additional friction torque may be set to “0” instead of performing the control for reducing the additional friction torque as described above. That is, it is good also as not performing friction provision control. In other words, hysteresis control may be turned off.

(When LKA is working)
Next, a method of changing the additional friction torque performed when the lane keep assist control is working will be described. The lane keep assist control corresponds to control for assisting the vehicle to travel in the vehicle lane.

  In the present embodiment, the controller 30 reduces the additional friction torque when the lane keep assist control is working, compared to when the lane keep assist control is not working. That is, the hysteresis control level is lowered. Specifically, the controller 30 acquires a control flag for lane keep assist control (hereinafter referred to as “LKA control flag”) from an ECU or the like in the vehicle, and the LKA control flag is on. Then, control is performed to reduce the additional friction torque. This is because it is desirable to make the steering wheel 1 easier to steer by reducing the friction torque when the lane keep assist control is working.

  More specifically, the controller 30 performs control to decrease the additional friction torque only when it is determined that the assist torque command value in the lane keep assist control constantly fluctuates and corrective steering is performed. . Alternatively, instead of the control for reducing the additional friction torque, the controller 30 sets the additional friction torque to “0” (that is, the friction applying control is not performed). On the other hand, the controller 30 does not perform control to reduce the additional friction torque when the command value of the assist torque is equal to or lower than a certain level in the straight traveling state. That is, the level of hysteresis control is not lowered.

  By controlling the additional friction torque when the lane keep assist control is operating as described above, the interference between the lane keep assist control and the friction applying control can be appropriately suppressed.

(When ACC is working)
Next, a method for changing the additional friction torque that is performed when adaptive cruise control is operating will be described. Note that adaptive cruise control corresponds to control performed to follow the vehicle while maintaining an appropriate inter-vehicle distance from the preceding vehicle.

  In the present embodiment, the controller 30 reduces the additional friction torque when the adaptive cruise control is working, as compared to when the adaptive cruise control is not working. That is, the hysteresis control level is lowered. Specifically, the controller 30 acquires an adaptive cruise control control flag (hereinafter referred to as an “ACC control flag”) from an ECU or the like in the vehicle, and is added when the ACC control flag is on. Control to reduce the friction torque. This is because it is desirable to make the steering wheel 1 easier to steer by reducing the friction torque when the adaptive cruise control is working.

  By controlling the additional friction torque when the adaptive cruise control is operating as described above, interference between the adaptive cruise control and the friction applying control can be appropriately suppressed.

  The present invention can be used for a vehicle having a power steering device configured to be able to apply torque to the steering.

In one aspect of the present invention, a power steering device mounted on a vehicle, based on information representing a vehicle state, friction torque setting means for setting a friction torque to be applied to the steering, and based on the friction torque A target steering angle setting means for setting the target steering angle, and a torque applying means for performing control for determining an additional friction torque based on a deviation between the target steering angle and the actual steering angle and applying the additional friction torque to a steering wheel. comprising the, if the behavior control of the vehicle acts, in response to said vehicle behavior control, and additional friction torque changing means for changing the adding friction torque, the.

Claims (7)

A power steering device that sets an additional friction torque to be applied to a steering based on an actual steering angle and a target steering angle, and performs control to apply the additional friction torque;
A power steering apparatus comprising: an additional friction torque changing unit that changes the additional friction torque in accordance with the behavior control of the vehicle when the behavior control of the vehicle is performed. The vehicle behavior control corresponds to traction control,
2. The power steering apparatus according to claim 1, wherein the additional friction torque changing unit increases the additional friction torque when the traction control is activated as compared with a case where the traction control is not activated. The vehicle behavior control corresponds to the anti-lock brake control,
2. The power steering according to claim 1, wherein the additional friction torque changing unit increases the additional friction torque when the control of the antilock brake is activated, compared with the case where the control of the antilock brake is not activated. apparatus. The vehicle behavior control corresponds to vehicle stability control,
2. The power steering apparatus according to claim 1, wherein the additional friction torque changing unit increases the additional friction torque when the vehicle stability control is activated as compared with a case where the vehicle stability control is not activated. The vehicle behavior control corresponds to vehicle integrated control,
2. The power steering apparatus according to claim 1, wherein the additional friction torque changing unit reduces the additional friction torque when the vehicle integrated control is operated, as compared with a case where the vehicle integrated control is not operated. The vehicle behavior control corresponds to lane keep assist control,
2. The power steering according to claim 1, wherein the additional friction torque changing unit reduces the additional friction torque when the lane keep assist control is performed, compared to when the lane keep assist control is not performed. apparatus. The vehicle behavior control corresponds to adaptive cruise control,
2. The power steering apparatus according to claim 1, wherein the additional friction torque changing unit reduces the additional friction torque when the adaptive cruise control is operated, as compared with a case where the adaptive cruise control is not operated.

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